The present invention relates generally to oral-nasal gastric tubes and more specifically to a tube of variable stiffness to facilitate insertion and comfortable use thereof.
During medical treatment it is frequently necessary to force feed patients who are unable to swallow, or who must be fed continuously with a liquid nourishment substance. Some medications, such as those used in the treatment of duodenal ulcers or bleeding stomach ulcers must be introduced directly into the stomach continuously or at frequent intervals. Even if the patient is able to swallow, the schedule of medication necessitates consuming small amounts of medication at frequent intervals, thus preventing sleep and other activities.
A variety of indwelling oral-nasal gastric tubes have been developed to allow food or medication to be administered when a patient is asleep or is unable to swallow. Such tubes are normally introduced through the nose or the mouth and pushed down through the esophagus into the stomach of the patient. The tube must be relatively stiff in order to pass through the nasal and esophageal areas, but this same stiffness of the tube is uncomfortable to the patient and frequently produces complications since the tube when in use comes into contact with a surface area of sensitive internal tissue. The most common complication which arises in the use of such tubes is necrosis due to tube pressure on the nares and the larynx. Another common complication is regurgitation of acid peptic stomach contents into the esophagus. This happens because the stomach contents seep alongside the tube into the esophagus. The reflux of stomach contents produces a severe esophagitis which can cause stricture or perforation of the esophagus.
U.S. Pat. No. 4,114,625 discloses a balloon gastric tube in which the balloon is inflated to block the space around the tube where the esophagus meets the stomach. The inflated balloon prevents acid stomach contents from rising into the esophagus around the tube, and the tube itself includes at least one passageway for the passage of air in order to equalize the pressure in the stomach with the atmosphere surrounding the patient. Other references utilizing balloons are disclosed in the intubation device of U.S. Pat. No. 4,166,468 and the nasogastric catheter of U.S. Pat. No. 4,180,076.
U.S. Pat. No. 2,498,692 discloses a steerable gastrointestinal tube. The tube may be directed during insertion by pulling either one of two wires mounted on opposite sides of the tube. When a wire is pulled, the tip of the tube turns toward the wire.
None of the patents mentioned above address the problem of unnecessary tube stiffness after insertion is completed. U.S. Pat. No. 4,182,342 discloses a gastric tube comprising a semi-rigid flexible feeding tube left behind after the removal of the insertion tube. The portion of the insertion tube which remains outside of the body during insertion includes a large container for a coiled portion of the feeding tube. The feeding tube extends from the container through the insertion tube and the end of the feeding tube which extends just beyond the end of the insertion tube is enlarged so that it cannot pass back through the insertion tube. The end of the feeding tube within the container is also enlarged so that it cannot pass beyond the container. In use, the insertion tube is inserted and then is pressurized to force the coiled feeding tube through the insertion tube and into the stomach. The insertion tube is then removed, leaving the feeding tube in place. The feeding tube can then be severed from the insertion tube and used for medication and feeding. However, the device features serious drawbacks in that it requires a number of passes through the esophagus in order to install the feeding tube, and the feeding tube is necessarily of relatively small diameter in order to fit within the insertion tube. Also, the rigidity of the insertion tube is fixed.
Thus, it can be seen that there is a need in the art for an oral-nasal gastric tube of variable stiffness in order to facilitate insertion and thereafter minimize patient discomfort and complications and which also reduces the number of passes through the esophagus which are needed to install the device.